1. Field of the Invention
The present invention relates to flexible bags and, more particularly, to sterile disposable plastic bags for use in handling various liquids.
2. Description of the Prior Art
Various bags have been developed for the sterile transportation and/or storage of samples in the medical and food fields, such as human fluid samples, milk, water in environmental studies, etc.
Such a plastic bag is disclosed in U.S. Pat. No. 5,564,829 issued on Oct. 15, 1996 to Lafond. As seen in FIG. 3, in this patent a disposable sterile plastic bag B comprises a two-ply sheet flexible material consisting of front and rear sheets 8 integrally joined at opposed side edges 12, 12 thereof (or the bag may be made from a tube) and including opposite upper and lower ends 10 and 14, respectively. The front and rear sheets 8, 8 are joined at the upper and lower ends 10 and 14 thereof respectively by upper and lower heat seals 16 and 18, respectively, with a sealed sample receiving chamber being defined between the two plastic sheets 8, 8 inwardly of the bag's side edges 12, 12 and upper and lower sealed ends 16 and 18. Inwardly of the upper seal 16, there is defined a tear-off line 20 transversely across the two sheets 8,8 and parallelly to the upper seal 16 thereby forming a detachable strip 24 outwardly of the tear-off line 20. The tear off line 20 is punctured through both sheets 8 across the upper end 10 of the bag B and lower than the upper heat seal 16 such that the upper heat seal 16 extends substantially parallelly between the tear off line 20 and an upper edge 26 of the bag B. When the liquid sample is ready to be introduced in the bag B, the strip 24 is removed from the bag B by pulling it so as to cause rupture of the two sheets 8, 8 at the tear-off line 20. The bag's chamber is thus sterile when the sample is introduced therein and the bag B, when so opened, defines a mouth 22 through which the liquid sample may be introduced in the bag B. The bag's sterility does not depend on how the bag is packaged or on the integrity of the packaging's seal as the bag is itself sterile until the strip 24 is removed therefrom, that is until the bag B is ready to be used.
Such plastic bags may also include near an open end thereof a wire or metal strip which is mounted transversely across the bag with ends extending past the side edges of the bag. Once the bag has been filled with the sample to be transported/stored, the open end is folded at least once over the bag about the wire or metal strip so as to close the open end and the ends of the wire or metal strip are then folded at the side edges of the bag and brought around so as to extend inwardly behind the bag. This safely and effectively encloses the sample in the plastic bag.